Adsorption is the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface. This process creates a film of the adsorbate (the molecules or atoms being accumulated) on the surface of the adsorbent.
Activated carbon (AC) is a widely used adsorbent for removal of pollutants from gas and water streams, and is conventionally made by pyrolysis and activation of carbonaceous precursor materials. Activation of oil sands coke with steam and/or CO2 may need 1 to 6 hours of heating in a tube furnace and results in an activated carbon with maximal methylene blue adsorption of 100.5 mg/g at 4 hours heating. Microwaves may be used in the activation process.